@MidwestMTMom - you’ve come to the right place. It’s great that you are here for your junior and middle schooler. Here are a couple of threads from past years’ seniors telling about background training, schools applied to/accepted/rejected, what could have been different. Lots to digest, but gives a good overview of what to expect.
http://talk.collegeconfidential.com/musical-theater-major/1724734-final-decisions-background-class-of-2019-p1.html
http://talk.collegeconfidential.com/musical-theater-major/1616849-final-decisions-background-class-of-2018-p1.html
The same thread for Class of 2020 is also out there and just “ramping up”.